Legibility of health warnings on billboards that advertise cigarettes

At present only subjective criteria exist to determine the legibility of health warnings on billboards that display advertisements for cigarettes. We constructed a set of objective standards and used them to assess the legibility of warnings on a sample of 37 billboards in Perth, Western Australia. The three features that were analysed were the apparent size of the letters, the colour contrast between the letters and their background, and the obliqueness of the message. We also compared the size and legibility of the health warning with that of the brand name. Health warnings were not legible to passing motorists in 51% of cases and not legible to motorists who were stopped at nearby intersections in 74% of cases, whereas almost all the brand names could be read easily. These results indicate that the present system of voluntary regulation of advertisements for cigarettes has failed to ensure that health warnings on billboards are legible. For health warnings on advertisements to have any useful effect it is essential that they are legible. The only way to ensure legibility is to adopt objective requirements for it.